Di2 Battery Holder for 25.4 mm Seat Posts


This battery holder is for Shimano Di2 internal SM-BTR2 and BT-DN110 batteries. The battery fits inside the seat post and typically requires a seat post made specifically for Di2. This holder allows the battery to be held securely within a non-Di2 specific 25.4mm seat post found on many bikes from 2014 to present. It will also fit other seat posts with the same inside diameter.
Weight:  11-12g

Made from hard, tough, and tear resistant rubber.  Completely protects the delicate battery connector.

Collections: Di2-eTAP Conversion Accessories

Battery Holder Sizes

We make Di2 battery holders for 25.4mm seat posts with various inside diameter size options primarily for Cannondale seat posts.  If you are using a non-Cannondale or FSA seat post, measure the inside diameter with a caliper and round up.  If the measurement is more than .25 mm from the available sizes, or an odd shape, contact us for assistance.

Seat Post Sizes:

Cannondale Branded

C2 - 19 mm ID

C3 - 19.5 mm ID

FSA Branded

SL-K - 20.5 mm ID

Why use a holder instead of tape or foam?

Ad hoc solutions using tape and foam have multiple issues. The net result is often a damaged or stuck battery.

Problems with Tape or Foam:

  • They don't protect the delicate battery connection
  • Tape or foam can shrink, causing the battery to fall out
  • They can cause the battery to overheat
  • Tape, especially, can fuse to the inside of the seat post


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